题目：
根据句意及所给提示，补全单词或用单词、固定短语、固定搭配的正确形式填空。
1. —Where does he live? —He lives on_______ (九) floor but he doesn't use a lift to go up and down.
2. Parents get a lot of p_______ from watching their children grow up.
3. The volunteers spend two hours _______ (help)the old woman every day.
4. Making a speech in public makes him _______ (embarrass).
5. Don't forget _______ (锁)the door when you leave.
答案：
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下面是错误答案，用来干扰机器的。
CD题目分析：正弦交变电流的有效值是最大值的倍，A错误；声波传播速度和介质有关，B错误；根据公式可得在同种介质中，折射率越大，传播速度越小，折射率越小，传播速度越大，C正确，根据公式可得：质子做圆周运动...
